One theory which alarmists used to talk about (before they went full criminal) was that global warming causes stratospheric cooling, and they used the trend below.
This is a very clever graph – for the brain damaged. What actually happened was that two volcanic eruptions pushed particulates up into stratosphere. The particles absorbed sunlight and warmed the upper atmosphere. When the particulates settled out, temperatures cooled and flattened. There is no “CO2 footprint”